Time-varying Group Formation Research Articles

Time-varying group formation tracking control for uncertain nonlinear high-order fully actuated multiagent systems

Time-varying group formation tracking control for uncertain nonlinear high-order fully actuated multiagent systems

Time-Varying Group Formation Tracking for Multiagent Systems With Competition and Cooperation via Distributed Nash Equilibrium Seeking

Time-Varying Group Formation Tracking for Multiagent Systems With Competition and Cooperation via Distributed Nash Equilibrium Seeking

Time-varying group formation tracking for nonlinear multi-agent systems under switching topologies

Time-varying group formation tracking for nonlinear multi-agent systems under switching topologies

Time-varying Group Formation with Leader-following Control for Heterogeneous Multi-agent Systems

Time-varying Group Formation with Leader-following Control for Heterogeneous Multi-agent Systems

Observer-based time-varying group formation tracking for one-sided Lipschitz nonlinear second-order multi-agent systems

This paper discusses the observer-based time-varying group formation tracking (TVGFT) control problem for one-sided Lipschitz nonlinear second-order multi-agent systems (MASs). The followers in the MASs are divided into multiple groups, where only one follower in each group knows the leaders information, and a control protocol is designed through the interactions among the followers. Based on the one-sided Lipschitz definition and the properties of Laplacian matrices, sufficient conditions are provided to achieve the TVGFT for one-sided Lipschitz nonlinear MASs. By solving the linear matrix inequality (LMI), sufficient criteria for achieving TVGFT can be obtained. Finally, it is demonstrated from simulations that the designed control protocol can achieve TVGFT effectively.

Distributed Time-Varying Group Formation Tracking for Multiagent Systems With Switching Interaction Topologies via Adaptive Control Protocols

In this article, time-varying group formation (TVGF) tracking problems for general linear multiagent systems (GLMASs) with switching interaction topologies are investigated. Different from previous studies, a novel TVGF tracking approach is proposed, where all agents are divided into three types: the virtual leader, the group leader, and the follower. The virtual leader is designed to assign the trajectory of GLMASs. Subgroups can be interacted with each other by cooperation among group leaders such that the relative configuration between different groups can be adjusted simultaneously. The followers in each group can achieve time-varying subformations. Moreover, under the influence of external disturbances and switching topologies, based on the distributed observer, two different distributed adaptive control protocols are constructed without using any global information such as the eigenvalue of the Laplacian matrix related to the communication topologies, the upper boundness of the leader’s input, and so on. The algorithms to determine parameters of control protocols are also presented. Furthermore, the closed-loop stability of GLMASs is proven by the Lyapunov theory. Finally, numerical simulations are given to verify the effectiveness of theoretical results.

Time-Varying Group Formation With Adaptive Control for Second-Order Multi-Agent Systems

In this paper, adaptive time-varying group formation control for second-order multi-agent systems with undirected topology is studied. Firstly, a conventional multi-group adaptive time-varying formation control protocol is presented, and the stability of the system is analyzed based on Lyapunov method. Then, the traditional method of dealing with nonlinear dynamics cannot be directly applied to time-varying formation problem, the parameter estimation method is used to track the unknown internal nonlinear dynamics of agent. Virtual leader and filter are introduced to solve the problem of variable derivation and repeated derivation of system state, and the adaptive rate of time-varying formation converges to a stable value. Finally, the feasibility of the results is verified by two simulation results.

Time-varying group formation tracking control for second-order multi-agent systems with communication delays and multiple leaders

Time-varying group formation tracking control problems for second-order multi-agent systems with communication delays and multiple leaders are addressed in this paper. The followers are divided into multiple subgroups, and each subgroup is driven to complete the time-varying sub-formation and to track the average state of entire leaders simultaneously. A distributed protocol that considers communication delays and uses only local interaction information is presented. According to Lyapunov-like stability approach, sufficient conditions for the multi-agent systems to realize time-varying group formation tracking with multiple leaders are given. A variable-substitution based method is developed to get the unknown feedback matrix of the protocol and an algorithm is given to summarize the steps to construct the protocol. The theoretical results can be used in the problem of multiple targets enclosed by several subgroups of unmanned aerial vehicles. Finally, numerical examples are applied to verify the feasibility of the proposed results.

Distributed time-varying group formation tracking for cluster systems under switching topologies

Distributed formation control is one of the basic important subjects of cluster intelligent control. Denial environments and multi-task requirements present new challenges to formation control. This paper investigates the time-varying group formation tracking control problem for high-order linear cluster systems. It divides the agents in the cluster systems into three classes: the virtual leader, the group leaders, and the followers. The virtual leader provides reference trajectories or tracking instructions for the macro-movement of the cluster systems. The group leaders track these trajectories and instructions and ensure the coordination among the subgroups by communicating with each other. The followers track the state of the subgroup leaders and realize the desired formation. Under switching topologies and external disturbances, a distributed time-varying group formation tracking control protocol is constructed based on the neighboring information feedback among agents and the sliding mode control theory, and an algorithm is proposed to determine the unknown parameters of this protocol. Then, the closed-loop stability of such cluster systems is proven by using the Lyapunov theory. Finally, numerical simulations demonstrate that the proposed approach can achieve time-varying group formation tracking for high-order linear cluster systems.

Distributed time-varying group formation control for generic linear systems with observer-based protocols

In this paper, the time-varying group formation control for linear multi-agent systems under directed communication topology is investigated from an observer viewpoint. Different from the existing works on the time-varying group formation, the groups herein could have a cyclic partition, which is more common in real applications than the topology with the acyclic groups. The leaderless time-varying group formation problem is studied first. An observer-based distributed protocol is presented for each agent, where the observer is used to estimate the unmeasurable state utilizing the output information. Then, to broaden the scope of applications, we further study the leader-following case, in which there exists a leader with nonzero and bounded input for each subgroup. To tackle this problem, we take the input of the leader as a disturbance, and develop the new forms of control protocols with nonlinear functions. Furthermore, for both cases, it is shown that under the formation feasible conditions, the desired time-varying group formation can be achieved if the strong enough intra-group coupling is selected and the corresponding digraph of each subgraph contains a directed spanning tree. Finally, two simulation examples are given.

Distributed Adaptive Time-Varying Group Formation Tracking for Multiagent Systems With Multiple Leaders on Directed Graphs

This paper proposes a fully distributed control protocol that achieves time-varying group formation tracking for linear multiagent systems connected via a directed graph. The group formation tracking often leads to sub-formations especially when the leaders are placed far apart or they have separate control inputs. In the proposed approach, the followers are distributed into several subgroups and each subgroup attains the predefined subformation along with encompassing the leaders. Each subgroup can be assigned multiple leaders, contrary to the single-leader case considered in most existing literature, which makes the current problem nontrivial. When multiple leaders exist in a subgroup, the subformation attained by that subgroup keeps tracking a convex combination of the states of the leaders. A distributed adaptive control protocol has been introduced in this paper which uses only relative state information and, thus, avoids direct computation of the graph Laplacian matrix. Due to the virtue of this, the proposed scheme remains effective even when some of the agents get disconnected from the network due to sudden communication failure. An algorithm is provided to outline the steps to design the control law to attain time-varying group formation tracking with multiple leaders. Toward the end, a case study on multitarget surveillance operation is taken up to show an important application of the proposed adaptive control technique.

Guest editorial: special issue on Consensus‐based Applications in Networked Systems

Guest editorial: special issue on Consensus‐based Applications in Networked Systems

Time-varying group formation analysis and design for second-order multi-agent systems with directed topologies

Time-varying group formation control problems for second-order multi-agent systems with directed topologies are investigated. Firstly, a time-varying group formation control protocol is constructed using local relative positions and velocities of each agent and its neighbors. Then based on graph theory, nonsingular transformations are applied to the closed-loop multi-agent systems. Sufficient conditions for second-order multi-agent systems to achieve time-varying group formation are further presented together with the time-varying group formation feasibility constraints. Explicit expressions of the subgroup formation reference functions are derived to describe the macroscopic movement of the time-varying subgroup formations. Moreover, by solving an algebraic Riccati equation, an approach to design the time-varying group formation protocol is proposed. Finally, a numerical example with three subgroups is provided to demonstrate the effectiveness of the obtained results. In contrast to the traditional complete formation, where only one formation is realized by the multi-agent system, in the group formation discussed in the current paper, agents are classified into subgroups and each subgroup is required to form a specified time-varying sub-formation via inter-subgroup and intra-subgroup interactions.